Because of adverse effects associated with the administration of whole cell vaccine, development of improved pertussis vaccines is of high priority. The Food and Drug Administration is responsible for ensuring that these vaccines are both safe and effective. We have therefore developed a battery of assays to test the safety and potency of these vaccines. These assays test the vaccines for purity, lack of toxicity, lack of the ability to revert to a toxic form, and immunogenicity. In particular, efforts have been expended to develop a potency assay for acellular pertussis vaccine which can be used as a reliable measure of the reproducibility of manufacture of these vaccines. A standardized ELISA is currently being developed which will measure the immune response in mice to the four antigens found in acellular pertussis vaccines. These antigens are filamentous hemagglultinin, pertussis toxoid, 69 kDa protein, and fimbriae. GRANT=Z01BA07020 The Laboratory of Pertussis is responsible for routine control testing of pertussis vaccine potency and toxicity. The toxicity and potency of the pertussis vaccine component of licensed vaccines are tested before the product can be released. Control testing in the Laboratory of Pertussis is used to determine that the pertussis component of vaccine issued by U.S. licensed establishments have adequate and stable potency through the dating period and are free from untoward reactivity due to toxicity. Satisfactory estimates of potency, stability and protective units per total human immunizing dose are determined using mice as animal models. In addition, mice are used to determine vaccine toxicity by observing early and late weight changes. In addition to laboratory examination of each vaccine submitted for release, control testing involves reviewing the manufacturer's protocol for satisfactory production methods and control tests performed by the manufacturer. During the period described by this report, no significant changes in potency and toxicity of pertussis vaccines submitted for release were noted. When materials allow, the Laboratory of Pertussis also performs control testing on vaccines from foreign manufacturers and serves as a reference testing laboratory for the World Health Organization.